Rotary valve assembly for sieve beds for pressure swing adsorption control

ABSTRACT

A rotary control valve and a sieve bed module assembly for use in pressure swing adsorption processes to make enriched oxygen product gas for therapy in patients is disclosed. The valve includes a stepping motor with a single shaft extending between ends. At ends of the valve, an air side valve function and oxygen side valve function are provided. Each end includes a stationary plate (stator) with ports, and a disc (rotor) that rotates with the shaft, opening and closing ports to achieve the desired valve function. The valve is integrated into the assembly between two sieve beds and a product storage tank is directly coupled to the oxygen side. Placement of the motor, shaft, and movable parts in the valve and mounting of the beds, valve, and tank in the assembly, result in more compact designs. The motor can be programmed to obtain multiple, different PSA processes and flexibility.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the priority benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 62/355,986 filed on Jun. 29,2016, the contents of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure is generally related to oxygen concentrators, andin particular oxygen concentrators utilizing a rotary control valve forpressure swing adsorption (PSA) control, and methods relating thereto.

2. Description of Related Art

Oxygen concentrators are devices that use a source of compressed air, amolecular sieve (typically in the form of two sieve columns), and apressure swing adsorption (PSA) process. Generally, the oxygenconcentrators generate approximately 1-10 liters/minute of 86%-96%oxygen gas for oxygen therapy. U.S. Pat. No. 2,944,627 to Skarstromdescribes an example of an early gas fractionalization method which canconcentrate oxygen from air using molecular sieve and PSA process. U.S.Pat. No. 5,474,595 to McCombs describes an example of a known oxygenconcentrator utilizing four solenoid valves on the air side and a singlesolenoid valve on the product side. U.S. Pat. No. 5,183,483 to Servido,et. al describes an example simplified pneumatic circuit for an oxygenconcentrator that uses two 3-way solenoid valves on the air side and airside sieve bed pressure balancing to reduce the complexity and number ofvalves necessary to control a PSA process.

Many different PSA process cycles have been developed over the years,from two steps to ten or more steps per two-bed cycle, and each processrequires a sufficient number of valve functions to control the flow ofgas (according to the process definition).

Traditionally, when designing a product for high volume production, anyadvantages of the more complex PSA processes are typically measuredagainst the cost, size, weight and reliability of the additional valvesrequired. Often this costs-benefit analysis results in valves beingeliminated, thus sacrificing PSA process efficiency and flexibility. Inthe case where PSA process efficiency benefits are required, the costsand complexity of adding multiple valves are accepted as an undesirabletrade-off. The present disclosure addresses many of the shortcomings ofthe prior art.

SUMMARY OF THE INVENTION

It is an aspect of this disclosure to provide a rotary control valve.The rotary control valve has a product end comprising a product rotorand a product stator, and an air end comprising an air rotor and an airstator. The product rotor includes a plurality of cavities configuredfor alignment with ports in the product stator, and the air rotorincludes a plurality of cavities configured for alignment with ports inthe air stator. A shaft is operatively connected to the product rotorand the air rotor. A motor is configured to drive the shaft. The drivingof the shaft is configured to rotate the product rotor and air rotorrelative to their respective stators such that cavities in each of therotors selectively align with ports in their respective stators.

Another aspect provides a module assembly. The module assembly includesa rotary control valve that has a product end comprising a product rotorand a product stator, and an air end comprising an air rotor and an airstator. The product rotor includes a plurality of cavities configuredfor alignment with ports in the product stator, and the air rotorincludes a plurality of cavities configured for alignment with ports inthe air stator. A shaft is operatively connected to the product rotorand the air rotor. A motor is configured to drive the shaft. The drivingof the shaft is configured to rotate the product rotor and air rotorrelative to their respective stators such that cavities in each of therotors selectively align with ports in their respective stators. Themodule assembly also includes a sieve bed module configured to receiveair from the rotary control valve and to output product gas.

Yet another aspect provides a method for controlling a pressure swingadsorption (PSA) process using a rotary control valve that has a productend and an air end, the product end having a product rotor and a productstator and an air end having an air rotor and an air stator. The productrotor includes a plurality of cavities configured for alignment withports in the product stator and the air rotor includes a plurality ofcavities configured for alignment with ports in the air stator. Therotary control valve further includes a shaft operatively connected tothe product rotor and the air rotor, and a motor configured to drive theshaft. The method includes operating the motor; driving the shaft usingthe motor; and rotating the product rotor and the air rotor relative totheir respective stators as a result of the driving of the shaft. Therotating of the product rotor and air rotor selectively aligns cavitiesin the rotors with ports of their respective stators.

In accordance with embodiments, the motor can be programmed andcontrolled to move clockwise, or counter-clockwise, continuously, orintermittently in steps, at low, high, or variable speeds to obtainmultiple, different, PSA processes resulting in high degree of PSAprocess design flexibility.

Other aspects, features, and advantages of the present disclosure willbecome apparent from the following detailed description, theaccompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a rotary control valve in accordance withan embodiment;

FIG. 2 is a bottom plan view of the rotary control valve of FIG. 1;

FIG. 3 is a sectional view of the rotary control valve taken along line3-3 in FIG. 1;

FIG. 4 is a sectional view of the rotary control valve taken along line4-4 in FIG. 1;

FIG. 5 is a sectional view of the rotary control valve taken along line5-5 in FIG. 1;

FIG. 6 is a top view of a housing of the rotary control valve of FIG. 1being partially removed on a first side, showing a product stator and aproduct rotor, in accordance with an embodiment

FIG. 7 shows a detailed view of a driver and springs in the housing ofthe rotary control valve on the first side as shown in FIG. 6, with theproduct rotor removed, in accordance with an embodiment;

FIG. 8 is a bottom view of a housing of the rotary control valve of FIG.1 on a second side, showing an air stator and an air rotor removed fromthe housing and a driver and springs in the housing, in accordance withan embodiment;

FIG. 9 shows a bottom view of the rotary control valve, with the airrotor and air stator assembled therein;

FIG. 10 shows the rotary control valve of FIG. 1 having tubing attachedthereto;

FIG. 11 shows the rotary control valve of FIG. 1 assembled in a moduleassembly in accordance with an embodiment;

FIGS. 12, 13, 14, and 15 show a front side, end, back side, and bottomview of the module assembly of FIG. 11;

FIG. 16 shows a detailed view of a mounting surface in the moduleassembly for receiving the rotary control valve of FIG. 1, in accordancewith an embodiment;

FIG. 17 is an exploded view of the parts of the module assembly of FIG.11;

FIG. 18 is a sectional view of the module assembly taken along line18-18 in FIG. 11;

FIG. 19 is a sectional view of the module assembly taken along line19-19 in FIG. 11;

FIG. 20 shows the rotary control valve of FIG. 1 assembled in the moduleassembly in accordance with another embodiment;

FIG. 21 is a sectional view of the module assembly taken along line21-21 in FIG. 21;

FIG. 22 illustrates a schematic diagram of valves replaced by thedisclosed rotary control valve for a 4-step air side PSA process in thedisclosed assembly, in accordance with an embodiment;

FIGS. 23 and 24 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its second sideduring the 4-step process of FIG. 22, in accordance with an embodiment;

FIG. 25 is a chart illustrating feeds and exhausts of the beds in theassembly at each of the steps of the 4-step process of FIG. 22;

FIG. 26 illustrates a schematic diagram of valves replaced by thedisclosed rotary control valve for a 4-step double side PSA process inthe disclosed assembly, in accordance with an embodiment;

FIGS. 27 and 28 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its second sideduring the 4-step process of FIG. 26, in accordance with an embodiment;

FIGS. 29 and 30 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its first sideduring the 4-step process of FIG. 26, in accordance with an embodiment;

FIG. 31 is a chart illustrating the feeds, exhausts, and balancing ofbeds in the assembly at each of the steps of the 4-step process of FIG.26;

FIG. 32 illustrates a schematic diagram of valves replaced by thedisclosed rotary control valve for a 6-step oxygen side PSA process inthe disclosed assembly, in accordance with an embodiment;

FIGS. 33 and 34 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its second sideduring the 6-step process of FIG. 32, in accordance with an embodiment;

FIGS. 35 and 36 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its first sideduring the 6-step process of FIG. 32, in accordance with an embodiment;

FIG. 37 is a chart illustrating the feeds, exhausts, and balancing ofthe beds in the assembly at each of the steps in the 6-step process ofFIG. 32;

FIG. 37A is a pressure curve graph relating to the steps in the 6-stepprocess of FIG. 37;

FIGS. 38 and 39 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its second sideduring the 6-step process of FIG. 32, in accordance with anotherembodiment;

FIGS. 40 and 41 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its first sideduring the 6-step process of FIG. 32, in accordance with anotherembodiment;

FIGS. 42-43 show examples of how the stator and rotor are mountedtogether when assembled in the rotary control valve on the second side;

FIGS. 44-45 show examples of how the stator and rotor are mountedtogether when assembled in the rotary control valve on the first side;

FIG. 46 illustrates a schematic diagram of valves replaced by thedisclosed rotary control valve for an 8-step oxygen side PSA process inthe disclosed assembly, in accordance with an embodiment;

FIGS. 47 and 48 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its second sideduring the 8-step process of FIG. 46, in accordance with an embodiment;

FIGS. 49 and 50 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its first sideduring the 8-step process of FIG. 46, in accordance with an embodiment;

FIG. 51 is a chart illustrating the feeds, exhausts, and purging andbalancing of the beds in the assembly at each of the steps during the8-step process of FIG. 46;

FIGS. 52-59 demonstratively illustrate rotation of the feed and exhaustrotors of the rotary control valve in each of the steps 1-8 of the8-step process of FIG. 46;

FIG. 60 illustrates a schematic diagram of valves replaced by thedisclosed rotary control valve for a 10-step oxygen side PSA process inthe disclosed assembly, in accordance with an embodiment;

FIG. 61 is a chart illustrating the feeds, exhausts, purging, andbalancing of the beds in the assembly at each of the steps during the10-step process of FIG. 60;

FIGS. 62 and 63 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its second sideduring the 10-step process of FIG. 60, in accordance with anotherembodiment; and

FIGS. 64 and 65 show a first side and a second side, respectively, of anexemplary rotor for use in the rotary control valve on its first sideduring the 10-step process of FIG. 60, in accordance with anotherembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The disclosed rotary control valve and a molecular sieve bed moduleassembly is described herein as being used in pressure swing adsorption(PSA) processes, or a control flow processes or cycles, that arecommonly used to make enriched product gas, e.g., oxygen (O2). Such gascan be used, for example, in an O2 concentrator for delivery of oxygendrug therapy to patients. Generally, the molecular sieve bed moduleassembly generates approximately 86%-96% oxygen gas for oxygen therapy.

However, it should be understood that other types of devices for makingenriched product gas may implement a rotary valve or pressure swingadsorption process as disclosed herein, and thus should not be limitedto the described implementations.

FIGS. 1-5 illustrate one embodiment of a rotary control valve 10 forcontrolling a desired PSA process in a module assembly, such as anoxygen concentrator. The rotary control valve has a connector 16 forpressure sensing and an electrical connector 18 for powering andcontrolling the motor. The rotary control valve 10 has a product end 12at its top end and an air end 14 at its bottom end, and a motor 22 witha single shaft 24 extending in a vertical direction (vertical axis A)between both ends. The motor 22 drives the shaft 24, for example, aboutthe axis A. As the shaft 24 is rotated, internal components withinhousings 20, 21 at the ends 12, 14 of the valve 10 are opened and closedto achieve the desired valve function, as explained below.

The product end 12 of the rotary valve 10 is used to deliver product gas(e.g., oxygen) produced from sieve beds of an assembly. The product end12 of the rotary control valve 10 includes a housing 20 provided at atop end that contains an internal product valve therein. The housing 20includes a bottom part 38 and a top part 40. The bottom and top parts38, 40 are secured together using fasteners 44 (e.g., bolts), placedthrough aligned openings, and enclose internal components of the productend 12 therein. The positioning or direction of insertion of thefasteners is not limited (e.g., see FIGS. 4 and 5). The internalcomponents in the product end 12 include a product rotor 32 and aproduct stator 34, as seen in FIGS. 3 and 4, for example. The productrotor 32 and product stator 34 are contained within a chamber 56 oropening formed between a bottom part 38 and a top part 40 of the housing20. The chamber 56 may hold pressurized gas (O2) therein for delivery toa patient (via a delivery system). The bottom part 38 of the housing 20includes a delivery channel 58 that communicates the pressurized gas tothe connector 16, for delivery or feeding of gas (O2) out of the valve10 and to the patient (e.g., via hose or tubing connected to connector16). The top part 40 of the housing 20 includes connectors 17 forfeeding product gas through delivery channels 60 and into the chamber56. As shown and described later, the connectors 17 may have tubingconnected thereto for delivery of the product gas (oxygen) from sievebeds within a module assembly 100. Also, in an embodiment, the rotarycontrol valve 10 also includes an orifice 76 or opening forcommunicating product gas from a product tank (e.g., see tank 106 inFIG. 18) into the chamber 56. As seen in FIG. 4, the top part 40 of thehousing may include the orifice 76 therein for providing fluidcommunication directly with product storage tank 106.

The air end 14 of the valve 10 feeds air to sieve bed(s) of the assembly(which produces the output product gas (O₂) for delivery to a patient)and/or exhausts the sieve bed(s). The air end 14 of the rotary controlvalve 10 also includes a housing 21 provided at a bottom end of thevalve 10 that also contains internal components therein. The internalcomponents in the air end 14 include an air rotor 48 and an air stator50, also shown in FIGS. 3 and 4, which form an air delivery valve. Theair rotor 48 is contained within a chamber 54 or opening within thehousing 21. The air stator 50 encloses the air rotor 48 within thechamber 54. The chamber 56 may hold pressurized air therein. Asschematically shown in FIG. 22, for example, the rotary valve 10 isoperatively connected to a compressor 80 and a muffler 82. Thecompressor 80 is configured to compress atmospheric air and provide thecompressed air as a source of feed gas to the chamber 56 of valve 10.Pressurized air may be delivered from the chamber 56 to one or moresieve beds based on the relative position of the rotor and stator 48,50. Air may also be exhausted from the sieve beds and/or housing 21 viamovement of the rotor 48 via muffler 82. The configuration and use ofthe compressor 80 and muffler 82 within an oxygen concentrator isgenerally known, and thus not described in detail herein.

The rotors 32, 48 are discs that are operatively connected or coupled tothe shaft 24. The rotors 32, 48 are configured to simultaneously rotatewith the shaft 24 of the motor 22 about the axis. The rotors 32, 48include cavities therein that may align with one or more of ports of thestators 34, 50 during steps of a control process. As the rotors 32, 48rotate, ports of the stationary stators 34, 50 may be exposed (e.g., tofeed air), covered (partially or fully, to close a port), or connect aport to a center portion (e.g., open to exhaust, or open to product gasfrom a tank).

In an embodiment, each of the stators 34, 50 is provided in the form ofa stationary plate at each end 12, 14 of the rotary control valve 10that contain ports therein that lead to control nodes of an assembly(such as a module assembly 100, described with respect to FIGS. 11-19).For example, the plates may enclose the rotors 32, 48 within thechambers 56, 54 of the housings 20, 21 (respectively). In oneembodiment, the air stator 50 has three ports in a line, an example ofwhich is shown in FIG. 9. The center port 60 is an exhaust port thatconnects to and communicates with an exhaust portion of the system(e.g., see ports 112 and 116 in manifold 110, shown in FIGS. 14 and 16).The right and left ports 64, 66 on either side of the center port 60lead to relative feed ends of the sieve beds in the module assembly 100.In an embodiment, the product stator 34 has two ports 68, 70, such asshown in FIG. 6. The two ports 68, 70 lead to the oxygen end of thesieve beds. In another embodiment, the product stator 34 has threeports, i.e., a center port is added in addition to the ports 68, 70. Thecenter port may lead directly to a product (oxygen) storage tank (e.g.,see tank 106 in FIG. 18).

The rotors are operatively connected to the shaft 24 of the motor 22 viadrivers 30 and 46 for axial rotation. Specifically, in one embodiment, aproduct driver 30 is mounted to an end of the shaft 24 at the productend 12 and is operatively connected to the product rotor 32. An airdriver 46 is mounted to an opposite end of the shaft 24 at the air end14 and operatively connected to the air rotor 48. In an embodiment, theshaft 24 engages a connecting portion of each driver 30, 46. In anotherembodiment, the shaft 24 extends through a central opening providedwithin each driver 30, 46. The central opening of the driver and theshaft may have corresponding shapes, such that the driver and shaft maybe press-fit together, for example. FIG. 7 shows an example of the topend of the shaft 24 being press fit into an opening 74 of the driver 30at the product end 12, wherein the opening 74 has a shape thatcorresponds to the shape of the shaft 24 (e.g., a D-shaped shaft).

Each rotor and stator has a first side and a second side. The first sideof the stator faces its respective housing, while the second side of thestator faces its respective rotor. A first side of each rotor faces itsstator, while a second side (or underside) of the rotor faces itsdriver. In accordance with an embodiment, the second side of each rotorthat faces its driver may have a mating surface that corresponds to aconnective mating surface of its driver. The shaft 24 rotates thedrivers 30, 46, which in turn rotate the rotors 32, 48. As the shaft 24is rotated about its axis A, the product rotor 32 and the air rotor 48are correspondingly moved about axis A. The rotation of the shaft 24 isperpendicular to the sides (or faces) of the rotors. The rotors 32, 48rotate relative to their respective stators 34, 50. As they rotate, thecavities within the rotors 32, 48 selectively align with the ports inthe respective stators 34, 50, to achieve the desired valve function.Alignment of the cavities and ports in the rotary control valve 10allows flow to or from the fluidly connected sieve beds, for example.

To maintain engagement of the rotors and stators at each end 12, 14 ofthe rotary control valve, a combination of biasing force and pressuremay be used. As shown in FIG. 3, for example, biasing mechanisms 36 and52 are provided between the drivers 30, 46 and the rotors 32, 48(respectively) for biasing and sealingly engaging the rotors 32, 48towards their respective stators 34, 50. The force applied by thebiasing mechanisms 36 and 52 is designed such that it is greater than anopposing force and/or weight applied to the rotors 32, 48. In oneembodiment, the biasing mechanisms 36, 52 are in the form of coiledcompression springs. FIG. 7 shows an example of four (4) coil springsplaced relative to the driver 30 that are designed to force rotor 32upwardly towards and against the stator 34 when assembled in the housing20. Optionally, oxygen pressure formed within the chamber 56 of housing20 may also assist in holding the rotor 32 against the stator 34. FIG. 8shows an example of two (2) coil springs placed relative to the driver46 that are designed to force rotor 48 downwardly towards stator 50 whenassembled in the housing 21. Pressurized air contained within chamber 54may also provide pressure around air rotor 48 to assist with pushing therotor 48 downwardly against the stator 50.

A shaft seal on one or both ends of the rotary control valve 10 may beincluded to prevent or diminish any leakage that can occur between themotor shaft 24 and surrounding housing(s) 20 and 21. For example, asshown in FIG. 3, seal bearings 26 may be provided around the shaft 24within a bottom part 38 of housing 20 and within housing 21. In caseswhere the thrust load on the product side 12 of the valve exceeds thecapacity of the stepping motor 22, a thrust bearing 28 (also shown inFIG. 3) can be added to absorb this load, and protect the motor 22.

One or more O-rings or seals may be provided in and around the rotarycontrol valve 10. For example, an O-ring 42 is provided around housing20 to sealingly engage the valve 10 within a product storage tank 106 ofa module assembly 100, as seen in FIG. 18. O-rings 43 (see FIG. 3) maybe provided around connector 16 to sealing engage the connector withinan opening of the housing 20 (in the bottom part 38) for alignment withthe delivery channel 58. One or more O-rings 45 may also be providedbetween the stators 34, 50 and housings 20, 21 to sealingly secure thechambers 56, 54.

The motor 22 is provided between the product end 12 and the air end 14of the rotary control valve 10. The motor 22 drives the shaft 24 aboutthe vertical axis A for axial rotation either in a clockwise orcounterclockwise direction. As shown in FIG. 3, for example, the shaft24 extends through the motor 22 and beyond the ends of the motor 22 inboth directions. In an embodiment, bearings 26 (and/or 28) and drivers30, 46 are provided on the ends of the shaft 24, outside and adjacent toends of the motor 22. As shown in FIG. 1, the motor 22 is surrounded bysupport posts 23. The support posts 23 extend between and are attachedto the housings 20, 21. The posts 23 are used to secure the housings 20,21 together with the motor 22 therebetween to form as assembly. Theposts 23 assist in providing structural rigidity to the assembly. In anembodiment, the length of the posts 23 is consistent with the height ofthe motor 22. The posts 23 are releasably connected at either end to apart of the housings 20 and 21. For example, as shown in FIG. 4, in oneembodiment, the posts 23 may connect to housing 20 via receipt of anextension portion of housing 20 therein (e.g., within a center of eachpost), while fasteners 47 are used to secure the opposite end of theposts 23 to a lip of the housing 21. The tightening of the fasteners 47secures the housings 20, 21 together thus assuring that housing 20 doesnot rotate relative to housing 21.

In accordance with an embodiment, the motor 22 is a controllable orprogrammable stepper motor, controlled by a controller (not shown). Thecontroller may accelerate or decelerate the motor in a negligible orshort amount of time. The stepper motor 22 may be a hybrid motor havinga single, double, or triple stack. In one embodiment, the stepper motor22 may be a NEMA 17 size stepper motor (˜42 mm square)×30 mm-42 mm inlength, and have 200 steps per revolution.

The motor 22 is configured to rotate the shaft 24 through a 360 degreecycle and configured to stop rotation of the shaft 24 and dwell for aperiod of time at a number of positions or steps about the 360 degreerotation. Such cycles are also referred to as “PSA processes”, examplesof which are described later.

The connectors 17 in the top part 40 of the housing 20 of the rotarycontrol valve 10 are used to receive produced product gas (O2) from asieve bed. As shown in FIG. 10, the connectors 17 have one end of apiece of tubing 72 connected thereto. The other end of the tubing isconfigured for connection to a delivery port 128 within the moduleassembly 100 for delivery of the product gas from one or more sieve bedsof the assembly. FIGS. 11-19 illustrates features of an exemplary moduleassembly 100 configured to employ the rotary control valve 10 therein.The assembly 100 acts as an air separation device (i.e., capable ofseparating oxygen from air) using pressure swing adsorption technology.As shown, the disclosed design of the module assembly 100 integrates twomolecular sieve beds 102, 104, a product storage tank 106, and therotary control valve 10 into a compact, flexible, and scalable module.The molecular sieve beds 102, 104 are provided in the form of columnsthat include active molecular sieves therein which are designed toadsorb nitrogen from intake air and produce oxygen-rich gas. The inputto the sieve beds 102, 104 of the assembly 100 is compressed air, andthe output is enriched (e.g., 86-96%) oxygen product gas, which may bedelivered to a patient. Depending on the amount of air input and thecharacteristics and size of the sieve beds and valve ports, the outputcan vary from 3 LPM to 10 LPM of product gas. In one embodiment, theoutput is rated for 5 LPM oxygen output.

It should be noted that, although the module assembly 100 as disclosedherein is described as employing the rotary valve 10, otherconfigurations of valves may be used with the module assembly 100. Thatis, the type and design of control valve(s) used with module assembly100 is not intended to be limited. In accordance with an embodiment, oneor more valves may be provided in the module assembly 100 (e.g., such asknown solenoid valves, two-way valves, and/or three-way valves).

As shown in FIG. 12 and FIG. 14, for example, the columns of the twosieve beds 102 and 104 (also referred to herein as “Bed A” and “Bed B,”respectively) flank the rotary control valve 10 (or other controlvalve(s)) in the assembly 100. For explanatory purposes only, the moduleassembly 100 is shown and described below as using the disclosed rotarycontrol valve 10. The rotary control valve 10 assists in fluid flowbetween sieve beds 102, 104 for feeding the beds, equalizing orbalancing the beds, purging the beds, etc. during a selected PSAprocess. More specifically, the air end 14 of the valve 10 both deliversair to the sieve bed(s) 102, 104 and exhausts air from the sieve beds12, 104, as needed, while the product end 12 is used to deliver productgas (oxygen) from the product storage tank 106 (received via the sievebeds 102, 104) to the patient.

The rotary control valve 10 is positioned under the product storage tank106 (see FIGS. 12 and 14) to facilitate air and oxygen side control. Theproduct storage tank 106 stores the gas produced by the sieve beds, or“product gas” e.g., purified oxygen gas. The product storage tank 106 issecured in between the sieve beds 102, 104. In a non-limitingembodiment, the product storage tank 106 is centered between the sievebeds 102, 104, such that the centers of the tank and beds are linearlyaligned (see FIG. 11). In another embodiment, the centers of the tankand beds are provided in a triangular configuration (see descriptionwith regards to FIGS. 20 and 21). Despite the configuration, the producttank 106 is positioned above the rotary control valve 10. Morespecifically, the product storage tank 106 is linearly aligned with (ina vertical direction) and placed above the rotary control valve 10 toform a stacked configuration.

FIGS. 17, 18 and 19 illustrate the assembly of the product storage tank106 and the rotary control valve 10 in greater detail. The product tankis formed from the assembly of a first part 122 of an upper manifold 108and tube 126 with the rotary valve 10, as shown in FIG. 17. In anembodiment, an outer diameter OD of the rotary control valve 10 (e.g.,outer diameter of housing 20)(see FIG. 19) is of the same or lessdimension as an inner diameter ID of the tube 126 of the product storagetank 106. This allows for axial alignment of the valve 10 and the tank106 (e.g., centers are aligned along axis A), and so that tube 126 maybe coupled to the housing of the rotary valve 10. More specifically, inthe assembly, the tube 126 of the product storage tank 106 surrounds thetop part 40 of the housing 20 at the product end 12 of the valve 10 (seeFIGS. 18 and 19). In one embodiment, the tube 126 also extends around atleast a portion of the bottom part 38 of the housing 20. The O-ring 42is provided between an outer wall of the housing 20 and inner wall ofthe tube 126. Accordingly, the product/oxygen side valve function isdirectly coupled to the storage tank 106. Further, as seen in FIG. 18,for example, the product rotor 32 and product stator 34 of the internalcomponents on the product side 12 are substantially enclosed andprovided within the product storage tank 106.

Placement of these valve components within the product storage tank 106(and inside the sieve module envelope)—as opposed to valve placementoutside of the sieve module envelope, as in prior art systems—provideseasier mounting and connection of the valve 10 with the sieve beds 102,104. Moreover, multiple gas connections between multiple valves above,below, and/or to side of the sieve bed columns is reduced, and any size,weight and complexity issues because of multiple valve connections isdecreased.

The above-described configuration (stacked tank 106 and valve 10 that issecured together via O-ring 42) also greatly reduces and/or eliminatesany pressure leakage from the product storage tank 106. This provides asignificant cost reduction, since leakage is common in prior art designsand product gas (like O2) can be expensive to purchase and canister.Furthermore, if there is a leak of product gas in the disclosedconfiguration, the leak is designed for delivery into one or more partsof the module assembly 100, and thus can still be used for oxygentherapy.

To secure the molecular sieve beds 102, 104, a product storage tank 106,and the rotary control valve 10 into their compact configurations,manifolds 108, 110 may be used. An upper manifold 108 is provided on theproduct/oxygen side of the sieve beds 102, 104, as seen in FIG. 11 (ontop of the assembly 100). A lower manifold 110 is provided relative tothe air side 14 of the rotary control valve 10. In one embodiment, a topof each of the columns of the sieve beds 102 and 104 and a top of thetube 126 of the product storage tank 106 is secured to the uppermanifold 108. A bottom of each of the columns of the sieve beds 102 and104 and a bottom of the rotary control valve 10 is secured to the lowermanifold 110. The rotary control valve 10 may be secured in a center ofthe lower manifold 110, with Bed A/sieve bed 102 secured to the manifold110 on a left side of the valve 10, and Bed B/sieve bed 104 secured tothe manifold 110 on a right side of the valve 10 (see FIG. 12). Theproduct tank 106 is secured on top of the rotary valve 10 and in betweenthe beds 102, 104. In accordance with an embodiment, the top and bottommanifolds may be in the form of plates.

FIG. 17 shows one exemplary embodiment wherein the upper manifold 108includes two parts—a first part 122 and a second part 124—that connectand secure the product storage tank 106 and sieve beds 102, 104 togetherin the assembly 100. As shown in FIG. 18, the first part 122 of manifold108 includes a plurality of channels 132-136 therein for fluidlyconnecting the product storage tank 106 with the sieve beds 102, 104.The channels 132-136 receive product gas from the sieve beds 102, 104via orifices 142, 144. Specifically, the second part 124 includesorifice 142 for fluid communication with sieve bed A 102 and orifice 144for fluid communication with sieve bed B 104. The orifices 142, 144 maybe openings with o-ring seals therein, for example. Each of the orifices142, 144 connects to a respective tunnel 132 provided within the firstpart 122. The tunnels 132 are secured via plugs 140 provided at theirrespective ends on either side of the manifold 108. Each tunnel 132 alsohas at least two channels 134, 136 branching off in a downward directiontherefrom. Channel 134 includes a delivery port 128 (with optionalconnector therein) for delivery of the product gas to tubing 72connected to the rotary valve 10. Channel 136 connects to a one-wayvalve 138, e.g., a flapper valve, and feeds into the tube 126 of theproduct storage tank 106. The one-way valve 138 may made of rubber, forexample, and designed to be forced open when pressurized product gasfrom one or more of the sieve bed(s) exceeds a specified amount, so thatthe product gas is fed into the tank 106. As such, the two-part manifold108 as direct flow of product (oxygen) towards the product storage tank106 and the product side 12 of the rotary control valve 10. The rotaryvalve 10 may receive product gas via delivery through tubing 72 andconnectors 17 and/or via orifice 76.

As shown in FIGS. 17-19, in some embodiments, tubing 72 and flow controlconnectors 17 are contained within the tube 126 of the product storagetank 106. Thus, the tubing, fittings, and/or hoses are unexposed.

The lower manifold 110 also includes a number of ports and fluidlyconnected channels therein. As shown in FIG. 14, a back of the lowermanifold 110 includes an exhaust port 112 for exhausting air from aninternal tunnel 146 (see FIG. 19) connected to the sieve beds 102, 104.The exhaust port 112 may expel gas from either of the sieve beds 102,104, e.g., through muffler 82, as a result of a pressure differential.

The internal tunnel 146 of lower manifold 110 may also be used todeliver air to the sieve beds 102, 104. The lower manifold 110 has aninlet port 114 for delivery of pressurized air from the compressor 80 tothe rotary control valve 10. Thus, the compressor 80 provides compressedair as a source of feed gas to a sieve bed on its feed side via thelower manifold 110. The inlet port 114 extends between a bottom surface(see opening in FIG. 15) and a top surface (see opening in FIG. 16) ofthe lower manifold 110. Optionally, in one embodiment, a fitting 86 (seeFIG. 19) is provided within the inlet port 114 for connection to one ormore parts of the compressor 80. As shown in FIG. 16, the lower manifold110 includes a center port 116 and side ports 118 and 120 that areconfigured to be selectively in fluid communication with ports 62 and64, 66 of the air stator 50 in the rotary control valve 10. When the airrotor 48 is rotated such that at least one of its cavities is at leastpartially aligned with one or more of ports of the stator 50,pressurized air may be directed to one or more of the sieve bed(s) 102,104.

As shown in FIG. 18, the internal tunnel 146 includes side branches 148for directing the air to the beds. The branches 148 extend from a centerof the manifold 110 towards the sieve beds 102, 104 and outer ends ofthe manifold 110. Each branch 148 has an opening 150, 152 that isrespectively aligned with sieve bed 102, 104 (e.g., port 150 is providedin a center of a sieve bed column) for delivering pressurized air. Anouter end of each branch 148 includes a plug 154 therein.

In addition to reducing the number of valves, required gas connections,size, and weight required for typical assemblies or oxygenconcentrators, the assembly of parts as described herein also assists inminimizing at least the longitudinal dimensions of the product storagetank 106 and the sieve beds 102, 104. As shown in FIG. 14, for example,sieve bed 102 (Bed A) has as height H1a and sieve bed 104 (Bed B) has aheight H1b. In the illustrated embodiment, the sieve beds 102, 104 areof similar height, i.e., H1a is equal to H1b (Ha1=H1b). The rotary valve10 has a height Hr and the product storage tank 106 has a height Hp. Inaccordance with an embodiment, the combined height of the valve 10combined with the height of the product storage tank 106—i.e., Hr+Hp—isapproximately equal to the height H1a or H1b of the sieve bed columns102, 104. In one embodiment, the combined height of the valve 10combined with the height of the product storage tank 106—i.e., Hr+Hp—isless than the height H1a or H1b of the sieve bed columns 102, 104.

The columns of the sieve beds 102, 104 also include an internaldiameter. Sieve bed 102 (Bed A) has a diameter of D1, and sieve bed 104(Bed B) has a diameter of D2, as shown in FIG. 12. In accordance withone embodiment, the diameters of the columns are substantially equal,i.e., D1 is equal to D2 (D1=D2). In an embodiment, the diameter ID ofthe product storage tank 106 is approximately equal to the diameters D1,D2 of the beds 102, 104. In another embodiment, the diameter ID of theproduct storage tank 106 is less than the diameters D1, D2.

In an embodiment, corner posts 130 (see FIGS. 12-14 and 17) are providedand secured between the upper manifold 108 and lower manifold 110 usingfasteners 84. The corner posts 130 to provide greater stability to theassembled beds 102, 104, valve 10, and product storage tank 106 in theassembly 100. The corner posts 130 also aid in pneumatic sealing of theparts in the module assembly 100.

In the embodiment described above with reference to FIGS. 17-19, thesieve beds 102, 104 and product storage tank 106 utilize tubes in alinear geometry (Sieve Bed A—product storage tank—Sieve Bed B), whichminimizes the depth dimension. As previously noted, in an alternateembodiment, the columns of the sieve beds 102, 104, product storage tank106, and rotary valve 10 are configured in an equilateral triangulararrangement, which is shown in FIGS. 20 and 21. In this triangulararrangement, the width and depth dimensions are approximately equal. Inyet another embodiment, the tubes of the sieve beds and product storagetank can be configured in a “L” or “Z” pattern, with each sieve bed 90degrees off axis relative to the product storage tank (not shown).Despite the configuration, with the rotary control valve 10 and theproduct 106 being positioned as previously described (e.g., in a stackedconfiguration and having a combined height substantially equal to orless than the height of the sieve beds), equally and “in between” thetwo sieve beds, the advantages and functionality of the module assembly100 is maintained.

Accordingly, the height dimensions of the beds and tank, in combinationwith the previously mentioned dimensions and configurations of theproduct storage tank 106 and rotary valve 10, ensure a compact module.Further, in accordance with an embodiment, the overall dimensions (depthand height) of the product tank 106 and valve 10 are not greater thanthe combined dimensions (e.g., diameter and height (length)) of thesieve bed columns. The integration of the valve, sieve bed, and productbuffer tank in this manner, results in a small, compact, lightweightoxygen generation module. The module assembly is scalable, and limitedonly by component availability.

Known assemblies tend to implement one particular gas separationprocess, with variables such as the time spent at each process step, andthe number of steps. However, the disclosed rotary control valve 10 andmodule assembly 100 are not limited to a single separation process.Instead, in accordance with embodiments herein, different variations ofthe rotor (and (optionally) stator) components, along with areprogramming of the controller for the motor 22, may be employed toaffect different gas separation process controls, i.e., a differentbalance or PSA process (e.g., from a 4-step to a 6-step process).Removal and replacement of the rotary valve 10 can be easily performedwithout disassembly of the sieve beds 102, 104 from the top and bottommanifolds 108, 110. Referring to FIG. 17, disassembly may begin bysimply disconnecting the columns 130 and the upper manifold plate 108from the lower manifold plate 110. This allows the removal of theproduct storage tank 106 (e.g., removal of tube 126) and the tubing 72,which then enables removal of the rotary valve module 10 from the lowermanifold 110.

In accordance with an embodiment, the entire rotary valve 10 is replacedwithin the module assembly 100 to change the PSA process. In anotherembodiment, the rotary valve 10 itself is disassembled to change the PSAprocess. For example, the housings 20, 21 may be unfastened and openedto replace the rotors 32, 48 (and optionally, the stators 34, 50)therein. The rotors 32, 48 may be provided in corresponding pairs suchthat they employ the selected process (e.g., for number of steps/steplength and dwell time). The stators 34, 50 need not be changed. However,in some embodiments, one or both of the stators 34, 50 may be changed orswapped, e.g., depending on the selected process, or based onconsiderations such as motor output torque (motor torque capabilityversus size).

Accordingly, in one embodiment, the selected rotor/stator combinationsand designs for the product side 12 and/or the air side 14 is dependentupon the step cycle to be employed using the rotary control valve 10.Generally, for each side, each of the rotors employed for a selected PSAprocess has a similar configuration. Using FIGS. 27 and 28 as anexample, shown are first and second sides, respectively, of an air rotor48 configured for use on the air side 14 of the valve 10 (in this case,in a 4-step DSB process). On the first side of the air rotor 48 in FIG.27, there is a provided a receiving portion 88 flanked by walls 90. Thereceiving portion 88 receives an end the shaft 24 of motor 22, and walls90 surround the end of the shaft 24.

Although two walls 90 are shown, any number of walls, including a singlewall, may be provided on the first side of the rotor 48 to surround theshaft 94. Multiple cavities 92 (shown here as circular holes) areprovided in an arc near one edge of the rotor 48. On the second side ofthe air rotor 48, as seen in FIG. 48, there is provided a first bellshaped depression 94. In one embodiment, a second depression 96 ofcorresponding shape is provided on the second side of the air rotor 48.FIG. 42 illustrates an alternate embodiment of a second side of an airrotor 48. This second side includes a protrusion on one side of therotor 48, with the bell shaped depression 94 provided therein.

FIGS. 29-30 illustrate an example of first and second sides,respectively, of a product rotor 32 (also referred to as an “oxygen siderotor”, below) configured for use on the product side 12 of the valve 10(in this case, in a 4-step DSB process). The first side of product rotor32 in FIG. 29 shows a connector 98 for connection to the product stator50. In one embodiment, as shown in FIG. 29, the second side of the rotor32 includes two kidney-shaped ports 78A that communicate with openings78B (see FIG. 30) provided on the second side of the rotor 32. The ports78A, 78B are configured to open or close communication between the sievebeds 102, 104 as it rotates between steps in a PSA process. The secondside of the product rotor 30 has a receiving portion 88A, withsurrounding extended walls 90A, for receipt of the opposite end of theshaft 24 of the motor 22. Again, although four walls 90 are shown, anynumber of walls, including a single wall, may be provided on the secondside of the rotor 32.

In another embodiment, such as shown in FIGS. 44 and 45, for example,the product rotor 32 does not include communicating ports and openings,but instead includes depressions for connection and fluid communication.FIG. 44 illustrates a second side of a product rotor 32 with analternately shaped receiving portion 88B. Indents 35 are provided in thebody of the rotor 32 for receipt of the biasing mechanisms 36 (providedbetween the rotor and driver 30). On the first side of this productrotor 50, as shown in FIG. 45, there is provided a symmetricaldepression 94A. The symmetrical depression 94A is configured to open orclose communication between the sieve beds 102, 104 as it rotatesbetween steps in a PSA process. The design of the depression 94A allowsfor communication between the beds even as the rotor rotates between twosteps of the process. In other words, there can be a change of state ofthe “valves” on the air side, and no change of state of the “valves” onthe oxygen side, due to this feature.

The number, size and/or dimensions of the above described cavities,depressions, and ports vary depending upon the selected step processbeing employed by the module assembly 100.

As previously mentioned, the motor 22 is programmable to implementdifferent PSA balance processes or cycles to rotate the shaft 24 (andthus the rotors 32, 48) through a 360 degree cycle to feed, balance,purge, etc. gases between the sieve beds 102, 104 and product storagetank 106, for example. The PSA cycles controllable and employed by therotary control valve 10 and module assembly 100 disclosed herein includethose with one, two, or three step feed phase and a zero, one, or twostep equalization phase. As noted herein, an oxygen side balanceprocess, or OSB process, is a PSA process step where the pressurebalance occurs by opening valves on the product (O2) side of the sievebeds. In addition, the compressed air is fed to one sieve bed at a time,never both, and the exhaust ports of each bed are closed during thebalance steps to assist with the balancing. In a true OSB process, thereare no overlapping feed valves and the exhaust valves are closed duringbalance steps. However, it is understood by one of ordinary skill in theart that very slight overlap may occur in some cases, e.g., to smoothout any load on the compressor.

In each PSA balance cycle, the stepping motor 22 is programmed to find ahome position (or zero position), and then progress through two or moresteps in a 360 degree cycle. A step includes rotating the rotors 32, 48(via rotation shaft 24) from one position to another position, stopping,and dwelling for a period of time. Accordingly, the locations forstopping rotation about the 360 degree cycle may be determined based onthe division of the full cycle by the desired number of steps (e.g.,360/# steps). In accordance with embodiments as disclosed herein, thedisclosed rotary control valve 10 may employ in 2-, 4-, 6-, 8-, and10-step gas separation processes, for example. As such, a two-stepprocess includes steps every 180 degrees. A four step process wouldinclude steps/stops every 90 degrees. A six step process would includestops every 60 degrees. An eight step process would include steps every45 degrees. A ten step process would include stops every 36 degrees.

The dwelling time at each step may be determined based on testing andexperimentation.

Several exemplary methods of employing a selected balance process usingthe disclosed rotary valve 10 and module assembly 100 in an oxygenconcentrator are described in greater detail below. One of ordinaryskill in the art shall understand the processes, implementation, andeffects associated with each step noted below, including feeding,equalizing, balancing, and purging the sieve beds. Accordingly, featuresassociated with each step for each noted balance process, are notnecessarily described in great detail. Generally, however, it is notedthat the act of feeding a bed includes delivering air to a bed using anair side 14 of the valve 10. In some cases, feeding may include feedingair and purified oxygen gas to a sieve bed. Exhausting a bed includeswithdrawing any gases from the bed. In some cases, the bed pressure maybe higher than atmospheric pressure, and thus opening a valve, e.g., toexpel through muffler, will allow exhaust flow out of the bed. In othercases, the exhaust may be via force, e.g., through suction, and muffler82.

Balancing the beds, also referred to as equalizing the beds, refers tobalancing or equalizing gas flow—and thus the pressure—between the beds.Reference to pre-balancing (Bal(Pre)) and post-balancing (Bal(Post))refers to first and second parts of balancing steps, respectively. Thatis, a first part of balancing (Bal(Pre)) is before a point of equalpressure balance (e.g., both being fed), whereas the second part ofbalancing is after the point of pressure balance. The connection of thebeds during balancing or equalizing is on the oxygen side (product side,or top side), of the beds. Purging refers to connecting the bedstogether such that one bed (e.g., bed A) delivers gas to the other bed(e.g., bed B). Thus, purging bed B refers to bed B having a pressureincrease because of (purge) gas received from bed A. Purging may beinduced by the application of pressurized air or gas into one of thebeds.

In one embodiment, a two-step PSA process, without a pressureequalization step, is implemented by the assembly 100 using the rotarycontrol valve 10. The rotors of the rotary control valve are rotated byrotating the shaft 180 degrees twice. The position of the shaft, andthus the position of the rotors, controls the feed to each sieve bed.For example, in an embodiment, at a shaft angle of zero degrees (or itshome position, or 360 degrees), Bed A is fed while Bed B is exhausted.At a shaft angle of 180 degrees Bed B is fed while Bed A is exhausted.

In a first illustrated exemplary configuration of an oxygenconcentrator, schematically shown in FIG. 22, a four (4)-step PSA airside balance process is implemented, by using the assembly 100, therotary control valve 10 and other system components, including thecompressor 80 and the muffler 82, which are schematically illustrated.FIGS. 23 and 24 show a first side and a second side, respectively, of anexemplary rotor 48 for use in the rotary control valve 10 on its airside 14 during the 4-step PSA air side balance process. The first side(FIG. 23) of the rotor 48 faces the driver 46, which is rotatablyconnected to the shaft 24 of the stepping motor 22. The angle of therotor (i.e., the rotation angle of the shaft which rotates the rotor toeach step) controls the percentage of air side balance. With this rotor48, the rotary control valve 10 provides functionality that isequivalent to two 3-way valves. In this 4-step PSA air side balanceprocess, only the air side is balanced in each step, and there is nooxygen side balance function. Valve 156 schematically represents theproduct feed (O2) into the product tank from the bed(s) via the productside 12 of the valve 10. One-way valves 138 are also schematically shownin FIG. 22.

More specifically, FIG. 25 is a chart illustrating examples of the feedsand exhausts of the Beds A and B at each of the steps of the 4-Step PSAair side balance process. In Step 1, wherein the angle of the shaft 24is zero (0), i.e., in a home position, Bed A receives feed while Bed Bis exhausted. The step time at Step 1 is approximately 5.00 seconds. InStep 2, at a shaft angle of 90 degrees, Beds A and B both receive feedfor a time of approximately 0.80 seconds, and thus the beds arebalanced. In Step 3, at a shaft angle of 180 degrees, Bed B is fed whileBed A is exhausted for a time of approximately 5.00 seconds. In Step 4,with the shaft rotated to 270 degrees in the cycle, Beds B and A areboth fed, and thus balanced, for a time of approximately 0.80 seconds.

Based on the exemplary step times noted above for each step, the totalcycle time of the rotary valve (to rotate 360 degrees) is approximately11.60 seconds.

In a second exemplary configuration of an oxygen concentrator,schematically shown in FIG. 26, a 4-step PSA double side balance (DSB)(i.e., air and oxygen side) process is implemented, using the assembly100, the rotary control valve 10, and other system components, includingthe compressor 80 and the muffler 82. FIGS. 27 and 28 show a first sideand a second side, respectively, of an exemplary rotor 48 for use in therotary control valve 10 on its air side 14 during this 4-step doubleside balance process. The first side (FIG. 27) of the air side rotor 48faces the driver 46 on the air side, which is rotatably connected to theshaft 24 of the stepping motor 22.

FIGS. 29 and 30 show a first side and a second side, respectively, foran exemplary rotor 32 for use in the rotary control valve 10 on itsoxygen side 12. The second side (FIG. 30) of the oxygen side rotor 32faces the driver 30 which is rotatably connected to the shaft 24 of thestepping motor 26 on the oxygen side. With these rotors 32 and 48therein, the rotary control valve 10 provides functionality that isequivalent to two 3-way valves and one 3-way valve. In this 4-step PSADSB process, in addition to balancing the air side in each step, atwo-valve function is added to the oxygen side, with both being balancedat each step (single step to balance the beds). The disclosed rotarycontrol valve enables the air side percentage to be reduced or adjustedin to accommodate the double side balance (whereas prior art systemsnormally have an air side that dominates the balance step). Valve 156schematically represents the product feed (O2) into the product tankfrom the bed(s) via the product side 12 of the valve 10. One-way valves138 are also schematically shown in FIG. 26.

More specifically, FIG. 31 is a chart illustrating examples of thefeeds, exhausts, and balancing of the Beds A and B in the assembly 100at each of the steps of the 4 Step PSA double side balance process. InStep 1, for a time of approximately 5.00 seconds, the angle of the shaft24 is zero (0), i.e., in a home position, and Bed A receives feed whileBed B is exhausted. In Step 2, at a shaft angle of 90 degrees, Beds Aand B both receive feed and are balanced for a time of approximately0.80 seconds. In Step 3, at a shaft angle of 180 degrees, Bed B is fedwhile Bed A is exhausted for a time of approximately 5.00 seconds. InStep 4, with the shaft rotated to 270 degrees in the cycle, Beds B and Aboth receive feed and are balanced for a time of approximately 0.80seconds.

Based on the exemplary step times noted above for each step, the totalcycle time of the rotary valve (to rotate 360 degrees) is approximately11.60 seconds.

In a third exemplary configuration, schematically shown in FIG. 32, asix (6)-step PSA oxygen side balance (OSB) process is implemented. FIGS.33 and 34 show a first side and a second side, respectively, of anexemplary rotor 48 for use in the rotary control valve 10 on its airside 14 during this 6-step OSB process. The first side (FIG. 33) of theair side rotor 48 faces the driver 46 which is rotatably connected tothe shaft 24 of the stepping motor 22. FIGS. 35 and 36 show a first sideand a second side, respectively, for an exemplary rotor 32 for use inthe rotary control valve 10 on its oxygen side 12. The second side (FIG.36) of the oxygen side rotor 32 faces the driver 30 which is rotatablyconnected to the shaft 24 of the stepping motor 22 on the oxygen side.

Alternatively, in another embodiment, rotors of a different design maybe utilized. FIGS. 38 and 39 respectively show a first side of anexemplary stator 50 in the form of a plate and a second side of anexemplary rotor 48, for use in the rotary control valve 10 on its airside 14 during a 6-step OSB process. The first side of the air siderotor 48 (the top of the rotor 48 as shown in FIG. 39) faces the driver46 on the air side. FIGS. 40 and 41 respectively show a first side of anexemplary stator 34 in the form of a plate and a first side of anexemplary rotor 32, for use on the oxygen side 12 of the rotary controlvalve 10. The first side (top side of the rotor 32 in FIG. 41, includingthe depression) of the oxygen side rotor 32 faces the respective driver30. FIGS. 42-43 show examples of how the stator 50 and rotor 48 of theair side are mounted together, when assembled in the rotary controlvalve. FIGS. 44-45 show examples of how the stator 34 and rotor 32 ofthe product/oxygen side are mounted together, when assembled in therotary control valve.

When either configuration of these rotors 32 and 48 is provided in therotary control valve, the rotary control valve 10 provides functionalitythat is equivalent to four 2-way valves and one 2-way valve. In this6-step process, two step balance is enabled by four times the 2-wayvalve functions on the air side. Valve 156 schematically represents theproduct feed (O2) into the product tank from the bed(s) via the productside 12 of the valve 10. One-way valves 138 are also schematically shownin FIG. 32.

FIG. 37 is a chart illustrating examples of the feeds, exhausts, andbalancing of the Beds A and B in the assembly 100 at each of the stepsin the 6-step OSB process. For a time of approximately 5.00 seconds inStep 1, the angle of the shaft 24 is zero (0), i.e., in a home position,and Bed A receives feed while Bed B is exhausted. In Step 2, at a shaftangle of 60 degrees, Bed A continues to receive feed and the balancingprocess of the beds begins (e.g., half balanced, or pre-balanced) (e.g.,such as by opening valve 156, at the top/oxygen side of the beds) for atime of approximately 0.40 seconds. In Step 3, at a shaft angle of 120degrees, Bed B receives feed and the balancing process continues for atime of approximately 0.40 seconds. After this time, the beds arebalanced (e.g., pressure is equalized via gas flow therebetween). InStep 4, at a shaft angle of 180 degrees, Bed B is fed while Bed A isexhausted for a time of approximately 5.00 seconds. In Step 5, at ashaft angle of 240 degrees, Bed B continues to receive feed and the bedsare pre-balanced for a time of approximately 0.40 seconds. In Step 6, ata shaft angle of 300 degrees, Bed A receives feed and the beds arepost-balanced for a time of approximately 0.40 seconds. After this time,the beds are again balanced.

Based on the exemplary step times noted above for each step, the totalcycle time of the rotary valve (to rotate 360 degrees) is approximately11.60 seconds.

FIG. 37A is a pressure curve graph showing the pressures (PSI) at eachsecond for air supply, O2 PSI, Bed A, Bed B, exhaust, and the O2 chamberand how they vary at each step during a repeated 6-step PSA cycle ofFIG. 37. More specifically, this graph shows approximately 23.2 secondsof data, which equates to two complete cycles of this specific process.

In a fourth exemplary configuration, schematically shown in FIG. 46, aneight (8)-step PSA oxygen side balance (OSB) process is implemented.

FIGS. 47 and 48 show a first side and a second side, respectively, of anexemplary rotor 48 for use in the rotary control valve 10 on its airside 14 during the 8-step OSB process. The first side (FIG. 47) of theair side rotor 48 faces the driver 46 which is rotatably connected tothe shaft 24 of the stepping motor 22. FIGS. 49 and 30 show a first sideand a second side, respectively, for an exemplary rotor 32 for use inthe rotary control valve 10 on its oxygen side 12. The second side (FIG.50) of the oxygen side rotor 32 faces the driver 30 which is rotatablyconnected to the shaft 24 of the stepping motor 22 on the oxygen side.With these rotors 32 and 48, the rotary control valve 10 providesfunctionality that is equivalent to four 2-way valves and one 2-wayvalve. The 8-step OSB process includes 2 step feed (with purge delayadded) and 2 step balance. Accordingly, two orifices 158 are providedadjacent to the oxygen sides of the beds A and B to control purge andlimit flow velocities. Valves may optionally be provided in the orifices158. One-way valves 138 to the product storage tank 106 are alsoschematically shown in FIG. 46.

FIG. 51 is a chart illustrating examples of the feeds, exhausts, andpurging and balancing of the Beds A and B in the assembly 100 at each ofthe steps during the 8 step OSB process. FIGS. 52-59 demonstrativelyillustrate rotation of the rotors 32 and 48 in each of the steps 1-8 ofFIG. 51, showing relative movement of the cavities, depressions, and/orports of the rotors 32 and 48 to the ports of the stators 34 and 50,with the shaft 24 moving the rotors to each step position of the 8-stepOSB process. FIG. 52 illustrates the rotors 32, 48 in a home position(1^(st) position). In Step 1, the angle of the shaft 24 is zero (0),i.e., in this home position, and Bed A receives feed (e.g., orifice(s)92 of rotor 48 are aligned with port 66 of stator 50) while Bed B isexhausted (e.g., bell shaped depression 94 of rotor limits communicationwith port 62 of air stator 50). The rotary control valve may dwell orstay in its position at Step 1 for a time of approximately 3.0 seconds.

FIG. 53 illustrates the rotors in a second position. In Step 2, at ashaft angle of 45 degrees, Bed A continues to receive feed (orifice(s)92 of rotor 48 are aligned with port 66 of stator 50), and Bed Bcontinues to exhaust (part of bell shaped depression 94 still limitscommunication with port 62 of air stator 50) as well as purge (viareceipt of gas from Bed A; e.g., bell shaped depression 94A of productrotor 32 moves in alignment with ports 68 and 70 of product stator 34 tofluidly connect the beds A and B), for a time of approximately 1.75seconds.

FIG. 54 illustrates the rotors in a third position. In Step 3, at ashaft angle of 90 degrees, Bed A receives feed and the beds are balanced(e.g., bell shaped depression 94A of product rotor 32 maintainscommunication with ports 68 and 70 of product stator 3). Also, bellshaped depression 94 of air rotor 48 moves away from alignment with anyof the ports of air stator 50. The rotary control valve may dwell orstay in its position at Step 3 for a time of approximately 0.5 seconds.

FIG. 55 illustrates the rotors in a fourth position. In Step 4, at ashaft angle of 135 degrees, Bed B is fed (e.g., orifice(s) 92 of rotor48 are aligned with port 62 of stator 50) and the beds are balanced fora time of approximately 0.8 seconds.

FIG. 56 illustrates the rotors in a fifth position. In Step 5, at ashaft angle of 180 degrees (from its home position), Bed B continues toreceive feed (via alignment of orifice(s) 92 and port 62), while Bed Ais exhausted (e.g., bell shaped depression 94 of air rotor 48 moves inalignment with ports 66) for a time of approximately 3.0 seconds. Also,bell shaped depression 94A of product rotor 32 moves away from alignmentwith any of the ports of product stator 34, thus stopping communicationbetween the beds. FIG. 57 illustrates the rotors in a sixth position. InStep 6, at a shaft angle of 225 degrees, Bed B continues to receivefeed, and Bed A continues to exhaust as well as purge (via receipt ofgas from Bed B; e.g., bell shaped depression 94A of product rotor 32moves in alignment with ports 68 and 70 of product stator 34 to fluidlyconnect the beds B and A). The rotary control valve may dwell or stay inits position at Step 6 for a time of approximately 1.75 seconds.

FIG. 58 illustrates the rotors in a seventh step. In Step 7, at a shaftangle of 270 degrees, Bed B receives feed (e.g., via orifice(s) 92 ofair rotor 48 being aligned with port 66 of air stator 50) and the bedsare balanced (via bell shaped depression 94A in rotor 32) for a time ofapproximately 0.5 seconds. FIG. 59 illustrates the rotors in an eighthposition. In Step 8, at a shaft angle of 315 degrees, Bed A is fed(e.g., orifice(s) 92 of rotor 48 are aligned with port 66 of stator 50)and the beds are balanced for a time of approximately 0.8 seconds.

Based on the exemplary step times noted above for each step, the totalcycle time of the rotary valve (to rotate 360 degrees) is approximately12.10 seconds.

Also shown in the illustrative embodiment of FIGS. 52-59 are utilizationof a cylindrically-shaped magnet 95 and a Hall-effect sensor 97. Theillustrated magnet 95 and sensor 97 of FIGS. 52-59 may be similarlyutilized in other embodiments and processes described herein and are notlimited to use in an 8-step process or with the illustrated rotors ofFIGS. 52-59. The magnet 95 is sensed by the Hall Effect sensor 97 tosignal (e.g., to the controller) that the home position has been found.This may be used during the start-up routine, for example, to establishan absolute rotational location for the motor shaft. The subsequentprocess steps (shaft rotation locations) are located a certain number ofdegrees from the home position. The magnet 95 and sensor 97 havespecifications to suit this purpose. Pins 99 are provided to connect therotating shaft to a rotating driver (not shown here for explanatorypurposes only; e.g., see drivers 30 and 46).

In a fifth exemplary configuration, schematically shown in FIG. 60, aten (10)-step PSA oxygen side balance (OSB) process is implemented bythe assembly 100. FIGS. 62 and 63 respectively show a first side of anexemplary stator 50 in the form of a plate and a second side of anexemplary rotor 48, for use in the rotary control valve 10 on its airside 14 during a 10-step OSB process. The second side (FIG. 63) of theair side rotor 48 faces the stator 50 on the air side. FIGS. 64 and 65respectively show a first side an exemplary stator 34 in the form of aplate and a first side of an exemplary rotor 32, for use in the rotarycontrol valve 10 on its oxygen side 12. The first side (top side of therotor 32 in FIG. 65) of the oxygen side rotor faces the stator 34.

When either configuration of these rotors 32 and 48 is provided in therotary control valve, the rotary control valve 10 provides functionalitythat is equivalent to four 2-way valves and three 2-way valves. In thisprocess, two-step balance is enabled as well as 3-step feed (double sidefeed (DSF) added) per 1/2 PSA cycle, totaling 10-steps per completecycle. The balance steps use some product storage tank gas, as does oneof the feed steps. Accordingly, in addition to two orifices 158 beingprovided adjacent to the oxygen sides of the beds A and B to controlpurge and limit flow velocities, a third orifice 160 is schematicallyprovided between the rotary valve 10 and product storage tank 106, forbleeding from the tank 106. The third orifice 160 may represent, forexample, the previously described orifice 76 as shown in FIG. 4. Valvesmay optionally be provided in the orifices 158, 160. One-way valves 138to the product storage tank 106 are also schematically shown in FIG. 46.

FIG. 61 is a chart illustrating examples of the feeds, exhausts,purging, and balancing of the Beds A and B in the assembly 100 based onthe movement of valves at each of the steps during the 10-step OSBprocess. In Step 1, the angle of the shaft 24 is zero (0), i.e., in ahome position, and Bed A receives feed while Bed B is exhausted. Bed Ais also purged in Step 1. The rotary control valve may dwell or stay inits position at Step 1 for a time of approximately one second. In Step2, at a shaft angle of 36 degrees, Bed A continues to receive feed, andBed B continues to exhaust. The rotary control valve may dwell or stayin its position at Step 2 for a time of approximately two seconds. InStep 3, at a shaft angle of 72 degrees, Bed A receives feed, Bed Bexhausts, and Bed B is purged of N2 using O2 from the product tank andBed A. The rotary control valve may dwell or stay in its position atStep 3 for approximately 2.0 seconds.

In Step 4, at a shaft angle of 108 degrees, Bed A is fed and the bedsare pre-balanced, for a time of approximately 0.40 seconds. In Step 5,at a shaft angle of 144 degrees, Bed B receives feed, and the beds arepost-balanced. The rotary control valve may dwell or stay in itsposition at Step 5 for a time of approximately 0.40 seconds. In Step 6,at a shaft angle of 180 degrees, Bed B continues to receive feed and ispurged, while Bed A is exhausted. The rotary control valve may dwell orstay in its position at Step 6 for a time of approximately one second.In Step 7, at a shaft angle of 216 degrees, Bed B continues to receivefeed, and Bed A continues to exhaust. The rotary control valve may dwellor stay in its position at Step 7 for a time of approximately twoseconds. In Step 8, at a shaft angle of 252 degrees, Bed B is fed, Bed Ais exhausted, and Bed A is purged of N2 using O2 from the product tankand Bed B. The rotary control valve may dwell or stay in its position atStep 8 for a time of approximately two seconds. In Step 9, at a shaftangle of 288 degrees, Bed B is fed and the beds are pre-balanced, for atime of approximately 0.40 seconds. In Step 10, at a shaft angle of 324degrees, Bed A is fed and the beds are post-balanced, for a time ofapproximately 0.40 seconds.

Based on the exemplary step times noted above for each step, the totalcycle time of the rotary valve (to rotate 360 degrees) is approximately11.60 seconds.

As such, as understood by the described balance processes above, thedisclosed rotary control valve 10 and module assembly 100 providesgreater flexibility in changing the process for oxygen delivery. Whileknown methods tend to implement one particular gas separation process,e.g., with the variables being the time spent at each process step, thedisclosed valve 10 and assembly 100 allows for use of differentvariations of the rotor and stator components, and a reprogramming ofthe stepping motor (via a controller), to affect a different gasseparation process control. Further, the rotary control valve 10 and/ormodule assembly 100 are easily scalable based on the system orenvironment it is employed in; for example, the valve 10 may be used insystems that are small, portable, and wearable, or system of largerscale, such as stationary or industrial size systems.

Because of the assembly and placement of parts in the disclosed rotarycontrol valve 10—including the placement and incorporation of the motor22 and shaft 24 between the symmetrically designed rotor/statorcombinations at each end 12, 14 of the valve 10—a more compactconfiguration of the rotary control valve 10 is established that isstill capable of implementing any number of step balance processes. Assuch, as demonstrated by the schematic drawings in FIGS. 22, 26, 32, 46,and 60, this one valve 10 replaces the functions of multiple solenoidvalves (e.g., up to nine solenoid valves, four on the air side, five onthe product side) that are conventionally used in known prior artdevices to control these same processes. Further, it eliminates extraconnections and controllers between parts of the assembly (e.g., eachprior art valve requiring piping connections, power, switching control,and timing input), as well as previous compromises made when consideringfactors of product output, separation efficiency, process complexity,size and materials cost.

The inherent symmetry of the design of the rotary control valve 10 leadsto symmetrical and equivalent flow rates for both halves of a PSA cycle.Asymmetrical flows of traditional solenoid valves can lead to less thanoptimum PSA performance, or require compensation via an offsettingcontrol technique, which adds uncertainty and complexity. Also, becausethe rotary control valve 10 provides both air side and oxygen side valvefunctions via a single motor, single shaft solution, the air separationprocess steps of the air side and the oxygen side valves are inherentlysynchronized, thus overcoming response time and control timingcomplexity of prior art solenoid valves. Additionally, a lead or lag inopening or closing a port can be designed in, if desired. The valvedesign allows for the possibility of designing a positive or negativeangular offset between the oxygen side and the air side. It also allowsfor the possibility of partially open and partially closed ports, if sodesired.

Further, traditional considerations and comprises—including cost, size,and weight of additional valves—are substantially if not entirelyeliminated based on the design of the disclosed rotary control valve 10.The functions of this valve 10 are easily changed and its inclusion ofreprogrammable components allows for different step processimplementations. The mechanical architecture is such that the cost,size, and weight of the control valve 10 is the same, independent of thechosen process. The end result is a configurable valve assembly thatexternally appears the same, and is considerable equal in manufacturingcost, weight, size, and power consumption, that is capable of employingand controlling simpler 4-step processes as well as more complex 6-, 8-,and 10-step processes.

The system and/or environment in which the rotary control valve 10 andmodule assembly 100 are used is not intended to be limited. For example,as previously noted the valve 10/could be applied to medical oxygenconcentrators used for supplemental oxygen therapy. It could also beused in industrial oxygen concentrators for non-medical use. The rotarycontrol valve 10 may also be employed in other industrial and/or medicalapplications where a simple, low cost, compact multi-port,multi-function valve designed to separate air and a product gas would bedesirable.

Further, as generally noted herethroughout, a number of additional partsmay be used with the module assembly 100 in an oxygen concentrator,although they may not have been illustrated or described in detailherein. One of ordinary skill in the art recognizes that sensors andother mechanisms may be used with the valve 10 and assembly. Forexample, a transducer may be connected to the compressor 80 to assist insteps of the different balance processes. In one example, the transduceris used to measure a certain amount (e.g., 1 psi) of purge gas used topurge the bed(s).

Also, the materials used to form the parts of the rotary valve 10 and/orparts of the module assembly 100 are not intended to be limiting. Inaccordance with an embodiment, the housings 20, 21 and any number of itsparts may be made of molded plastic. While materials such as plastics(e.g., Teflon) may be used to form or mold the rotors 32, 48, the platesof the stators 34, 50 may be formed from anodized aluminum (and machinedto include ports therein). Seals may be formed from rubber, for example.

While the principles of the disclosure have been made clear in theillustrative embodiments set forth above, it will be apparent to thoseskilled in the art that various modifications may be made to thestructure, arrangement, proportion, elements, materials, and componentsused in the practice of the disclosure.

It will thus be seen that the features of this disclosure have beenfully and effectively accomplished. It will be realized, however, thatthe foregoing preferred specific embodiments have been shown anddescribed for the purpose of illustrating the functional and structuralprinciples of this disclosure and are subject to change withoutdeparture from such principles. Therefore, this disclosure includes allmodifications encompassed within the spirit and scope of the followingclaims.

1. A rotary control valve comprising: a product end comprising a producthousing containing a product rotor and a product stator therein, theproduct housing comprising a chamber therein for receipt of the productrotor and, the product rotor comprising a plurality of cavitiesconfigured for alignment with ports in the product stator; an air endcomprising an air housing containing an air rotor and an air statortherein, the air housing comprising a chamber therein for receipt of theair rotor and, the air rotor comprising a plurality of cavitiesconfigured for alignment with ports in the air stator; a shaftoperatively connected to the product rotor and the air rotor; and amotor configured to drive the shaft, wherein both of the chambers areconfigured to hold pressurized gas therein; wherein the product statorand the air stator enclose their respective rotors within the chambersof the housings; and wherein driving of the shaft is configured torotate the product rotor and air rotor relative to their respectivestators such that the cavities in each of the rotors selectively alignwith ports in their respective stators.
 2. The valve according to claim1, wherein rotors are configured to be rotated to different positionsrelative to their respective stators by the shaft and the alignment ofthe cavities of the rotors with the ports in the stators is determinedbased on a step in a selected PSA balance process, wherein each positionis associated with one step in the selected PSA balance process.
 3. Thevalve according to claim 1, wherein the shaft comprises a shaftconfigured for axial rotation about an axis.
 4. The valve according toclaim 1, wherein the motor is provided between the stators. 5-6.(canceled)
 7. The valve according to claim 1, further comprising adriver at each of the product end and the air end, the drivers beingmounted to shaft, each driver being operatively connected to therespective rotors within the product end and air ends and configured torotate the respective rotors during driving of the shaft.
 8. The valveaccording to claim 7, wherein each rotor has a mating surfacecorresponding to connective mating surface of its driver.
 9. The valveaccording to claim 7, further comprising biasing mechanisms providedbetween the drivers and the rotors for biasing and sealingly engagingthe rotors towards their respective stators.
 10. The valve according toclaim 1, wherein the motor is a programmable stepping motor configuredto drive the shaft through a plurality of steps throughout a 360 degreecycle, wherein the product rotor and air rotor are configured to berotated to different positions relative to their respective statorsabout the 360 degree cycle.
 11. A module assembly comprising: a rotarycontrol valve comprising: a product end comprising a product housingcontaining a product rotor and a product stator therein, the producthousing comprising a chamber therein for receipt of the product rotorand the product rotor comprising a plurality of cavities configured foralignment with ports in the product stator; an air end comprising an airhousing containing an air rotor and an air stator, the air housingcomprising a chamber therein for receipt of the air rotor and the airrotor comprising a plurality of cavities configured for alignment withports in the air stator; a shaft operatively connected to the productrotor and the air rotor; and a motor configured to drive the shaft,wherein both of the chambers are configured to hold pressurized gastherein; wherein the product stator and the air stator enclose theirrespective rotors within the chambers of the housings; and whereindriving of the shaft is configured to rotate the product rotor and airrotor relative to their respective stators such that cavities in each ofthe rotors selectively align with ports in their respective stators, anda sieve bed module configured to receive air from the rotary controlvalve and to output product gas.
 12. The module assembly according toclaim 11, wherein the sieve bed module comprises two molecular sievebeds.
 13. The module assembly according to claim 11, further comprisinga product storage tank for holding the product gas produced by the sievebed module.
 14. A method for controlling a pressure swing adsorption(PSA) process using a rotary control valve, the rotary control valvecomprising a product end and an air end, the product end comprising aproduct housing containing a product rotor and a product stator thereinand an air end comprising an air housing containing an air rotor and anair stator therein, the product housing comprising a chamber therein forreceipt of the product rotor and the air housing comprising a chambertherein for receipt of the air rotor, the product rotor comprising aplurality of cavities configured for alignment with ports in the productstator and the air rotor comprising a plurality of cavities configuredfor alignment with ports in the air stator, the rotary control valvefurther comprising a shaft operatively connected to the product rotorand the air rotor; and a motor configured to drive the shaft; whereinthe method comprises: operating the motor; driving the shaft using themotor; and rotating the product rotor and the air rotor relative totheir respective stators as a result of the driving of the shaft,wherein both of the chambers are configured to hold pressurized gastherein during use of the rotary control valve; wherein the productstator and the air stator enclose their respective rotors within thechambers of the housings; and wherein the rotating of the product rotorand air rotor selectively aligns cavities in the rotors with ports oftheir respective stators.
 15. The method according to claim 14, whereinthe motor is a programmable stepping motor configured to drive the shaftthrough a plurality of steps throughout a 360 degree cycle, wherein theproduct rotor and air rotor are configured to be rotated to differentpositions relative to their respective stators about the 360 degreecycle, and wherein the method further comprises: driving the shaftthrough the plurality of steps throughout the 360 degree cycle; androtating the product rotor and the air rotor to different positionsrelative to their respective stators about the 360 degree cycle.